The subject matter disclosed herein relates to the technology of helical shuttle scan used in an X-ray CT (computed tomography) apparatus.
As is disclosed in Japanese Unexamined Patent Publication No. 2006-320523, the helical shuttle scan is a method of imaging, in which an X-ray generator and an X-ray detector are rotated while at the same time they are moved reciprocally and relatively in the z direction of a subject, which is the direction of body axis. FIG. 14 shows the relationship between the scan time and the velocity of the cradle in a helical shuttle scan, and the relationship between the scan time and the relative positions of gantry rotating device and the cradle. FIG. 14 shows an example of reciprocating motion, between predetermined imaging ranges z0 and z1, in the direction of body axis of the subject, by slowing down prior to stopping at z0 and z1, accelerating after stopping, and maintaining the speed during the intermediate range.